Lamp sockets for single pin fluorescent lamps



Aug. 23, 1955 M. H. KRUG ER LAMP SOCKETS FOR SINGLE PIN FLUORESCENTLAMPS Filed April 9, 1952 TEEN;

Ill

1 lNVENTOR MICHHEL HENRY KRUGER (A: ATTORNEY United States Patent LAMPSOCKETS FDR SINGLE PIN FLUORESCENT LAMPS Michael Henry Kruger, Maiden,Mass., assignor to A. L. Smith Iron Company, Chelsea, Mass., acorporation of Massachusetts Application April 9, 1952, Serial No.281,315

Claims. (Cl. 339 -55) This invention relates to sockets for fluorescentlamps in general and more particularly to lamp sockets for single pinfluorescent lamps.

With fluorescent lamps, and particularly with single pin fluorescentlamps where a low voltage circuit and a high voltage circuit are bothrequired to be established,

in the interest of safety, various contrivances have been devised toinsure that one circuit is not closed before the other circuit isclosed, and similarly that when removing a lamp, both circuits will beinterrupted simultaneously. To this end a fixed sleeve and a fixed seathave been provided for one pin and a yieldable seat for the other pin,the contact associated with the pin for the yieldable seat notcompleting a circuit until contact associated with the pin for the fixedseat is in contact, the pin associated with the fixed seat being barredfrom contact until after the pin associated with the yieldable seat hasbeen positioned. With these contrivances, however, difliculty has beenencountered in effecting a positive contact with the pin associated withthe yieldable seat.

With the foregoing in mind, the present invention aims to provide asocket having a yieldable seat which will insure a positive contact withthe pin associated with the yieldable seat when the pin associated withthe fixed seat is brought into contact and to maintain such positivecontact throughout the illumination of the lamp.

In practice, the authorities, such as the Underwriters Laboratory, haverequired with the conventionally fixed socket and yieldable socketbetween which a fluorescent lamp is positioned, that the contact disk ofthe yieldable socket be spaced not less than a predetermined distance,conventionally one-quarter of an inch from the outer face or outer seatof the yieldable socket to the contact disk. This requirement hascreated problems. As an instance, since the outer free end of the headof the contact pin of a fluorescent lamp is conventionally spherical, ithas been considered good practice to adopt a length of five-sixteenthsof an inch for the same extending from the outer free end of the head ofthe contact pin to the outer face of the cap of the lamp, thus allowingonesixteenth of an inch tolerance for the pin to find its final seat onthe contact. Normally, this one-sixteenth of an inch tolerance wouldpermit the desired positive contact between the pin head and the contactdisk in the yieldable.

socket. However, because of the difiiculty, from a manufacturingstandpoint, to produce uniform spherical forms for the free ends of thecontact pins, because of the difiiculty from a manufacturing standpointto produce uniformly formed round holes for the contact disksconstituting the seats for the contact pins, and because of othervariations from a manufacturing standpoint, this one-sixteenth of aninch tolerance does not always result in a positive contact, andconsequently objectionable arcing and accompanying burning of associatedparts is encountered.

According to the present invention a weaker spring is provided mainly tomaintain the contact disk the required 2,7 16,224 Patented Aug. 23, 1955further compression necessary securely to accommodate.

a fluorescent lamp between the yieldable socket and the fixed socket.Consequently, when the contact pin of a fluorescent lamp is insertedinto the yieldable socket,

(l) The initial pressure placed upon the yieldable socket is taken up bythe weaker spring to insure a positive contact between the outer freeend of the contact pin and the seat of the contact disk,

(2) The ultimate compression securely to accommodate the fluorescentlamp between the yieldable socket and the fixed socket is taken up bythe stronger spring,

(3) In inoperative position, that is when not supporting a lamp, theone-quarter of an inch space between the contact disk and the outer faceof the yieldable contact is maintained, and

(4) In operative position, that is when supporting a lamp, the spacebetween the contact disk and the outer face of the yieldable contact isalways slightly less than one-quarter of an inch and the tolerancelength of the contact pin of the yieldable socket is always slightlymore than one-sixteenth of an inch.

These and other features, capabilities and advantages of the inventionwill appear from the subjoined detailed description of specificembodiments thereof illustrated in the accompanying drawings, in whichFig. 1 is a transverse section of a socket fixture made according to oneembodiment, and the Wiring, lamp and lamp pin associated with the fixedseat illustrated diagrammatically.

Fig. 2 is a section on the line 22 of Fig. 1.

Figs. 3, 4, 5 and 6 are transverse sections of four additionalembodiments of the present invention.

Fig. 7 is an enlarged fragmental detail of the embodiment illustrated inFig. 1.

In the embodiment illustrated in Fig. 1, the improved socket fixture 1is shown in section and the connection thereof with a fixed socketfixture is shown diagrammatically. The fixture 1 consists essentially ofa housing section 2 composed of a suitable insulating material which hasa main terminal plate 3 provided with a screw 4 connected to the highvoltage conductor 5 which in turn is connected to the ballast ortransformer 6 from which, in the present instance, two conductors 7 and8 extend, the conductor 7 extending to one line of the source ofcurrent, and the conductor 8 extending to one of the twin contacts 9,the other twin contact 10 normally being spaced from the contact 9 andbeing connected by the conductor 11 to the other line of the source ofcurrent. The contacts 9 and 10 are positioned in the sleeve 12 adistance of about five-sixteenths of an inch from the fixed sockethaving the fixed seat consisting of the disk 13 provided with thecentral opening 14 to receive the spherical or rounded head of the pin15 of the single pin lamp 16. The other pin 17 of the lamp 16conventionally having a spherical or rounded outer free end is providedto cooperate with the yieldable socket having the yieldable seat 18.

The yieldable seat 18 consists of the disk 19, in the present instanceintegral with the sleeve 20, the disk 19 having an opening 21 to receivethe spherical or rounded head of the pin 15. The sleeve is slidablymounted in the cylindrical portion 22 of the housing section 23 securedto the main housing section 2. The main housing section 2 has a channel24 therein to receive the conductor portion 25 connected at one end tothe terminal plate 3 and at its other end being integral with the mainstrong spiral spring 26 which at one end surrounds the extension 27formed on the main housing 2 and disposed in axial alinernent with thecylindrical chambers in the portion 22 and sleeve 20, the spring 26extending from the extension 27 through the cylindrical chambers of theportion 22 and sleeve into engagement with the metal contact disk 28, inthe present instance provided with a round central opening 29, whichdisk 28 in turn engages the insulating washer 30 which forms the seat orabutment for one end of the weak spiral spring 31, the other end ofwhich spring 31 abuts against the disk 19 whereby the insulated housingsections 2, 20 and 22 composed of insulating material will supplementthe washer 30 to prevent the current from the terminal plate 3 to passto the pin 17 except through the disk 28.

The strengths and lengths of the springs 31 and 26 are determined sothat they have different loading factors, the spring 31 to resistgreater compression forces than the spring 26 will resist for thereasons now to be set forth. In practice, the authorities, such as theUnderwriters Laboratory, have required that the distance between theouter face of the contact disk 28 and the outer face of the disk 19 bepredetermined, conventionally onequarter of an inch. This requirementhas created problems. As an instance, due in part to the difliculty ofproducing uniformly shaped spherical forms for the outer free ends ofthe pins 17 and to produce uniformly shaped rounded openings 29 in thecontact disks 28, and due furthermore to the many other manufacturingvariations conventionally encountered, it has been considered goodpractice arbitrarily to adopt a length of five-sixteenths of an inch forthe lengths of the pins 17 measuring from the i outer free end of eachpin 17 to the outer face 33 of the cap of its associated lamp 16, thusallowing a tolerance of one-sixteenth of an inch for the pin to find itsfinal seat or, positive contact on the contact disk 28. Normally, thisone-sixteenth of an inch tolerance would permit the desired positivecontact between the head of the pin 17 and the contact disk 28 in theyieldable socket 18. However, because of the manufacturing variationsaforesaid, this one-sixteenth of an inch tolerance does not alwaysresult in a positive contact and consequently objectionable arcing andaccompanying burning of associated parts is encountered.

To overcome the aforesaid objection, according to the present invention,the loading factors of the springs 26 and 31 are in part determined tomaintain the distance between the outer face of the contact disk 28 andthe outer face of the disk 19 at the required predetermined distance, asan instance, one-quarter of an inch. Consequently, when the contact pin17 of the lamp 16 is initially inserted into the yieldable socket 18,

(1) The initial pressure placed upon the yieldable socket 18 will bemainly taken up by the weaker spring 31 to insure a positive contactbetween the outer spherical free end of the contact pin 17 and the seatof the contact disk 28,

(2) After the position of the pin 17 in positive con tact relationshipwith the contact disk 28 has been effected, and the consequent ultimatecompression of the spring 31 has been fixed, the ultimate compressionnecessary securely to accommodate the fluorescent lamp in positivecontact with the contacts of the yieldable and fixed sockets is taken upby the stronger spring 26,

(3) In inoperative position, that is, when not supporting a lamp, thepredetermined space required, one-fourth of an inch as an instance,between the contact disk 28 and the outer face of the yieldable contact18, is maintained, and

(4) In operative position, that is, when supporting a lamp, the spacebetween the contact disk 28 and the outer face of the disk 19 of theyieldable contact 18 is always slightly less than the predeterminedrequired distance, one-quarter of an inch as an instance, and thetolerance length of the contact pin 17 in the yieldable socket 18 isalways slightly more than one-sixteenth of an inch.

To anchor the sleeve housing section 23 to the housing section 2,screws, such as the screw 34, are provided which extend from thepartition 35 of the housing section 23 face of the sleeve 22 terminatingat 38 to receive projections, such as the projection 39, Fig. 2, on eachside of the sleeve 20.

The embodiment shown in Fig. 3 differs from the embodiment shown in Fig.1, primarily in that the insulating washer 30 is omitted and the sleeve22 omitted, and

in place of the latter the disk 40 is provided forming the yieldableseat which in turn is provided with an annular shoulder 41 to restagainst the shoulder 42 of the main housing 43 in expanded position ofthe springs 44 and 45. Here furthermore, the weak spring 44 is taperedwith its large coil disposed inside of the shoulder 41 and its smallcoil disposed inside of the shoulder 46 of the contact disk 47, whilethe small coil of the strong spring 45 is disposed on the outside of theshoulder 46 with the large coil of the spring 45 disposed in the openingformed in the disk 48, which in the present instance constitutes aconductor connected to the outgoing line 49.

The embodiment shown in Fig. 4 differs from the embodiment shown in Fig.1 primarily in that the insulating washer 30 is omitted, and that thesleeve 50 integral with the disk 51 constituting the yieldable seat,rides on the outside of the sleeve 52. Here furthermore, the largespring 53 is contained between the disk 54 at the inner end of thesleeve 52 and the flange 55 of the contact disk 56 with the small coilof the tapered weak spring 57 positioned adjacent the inside of theshoulder 155 of the disk 56, and the large coil of the Weak spring 57engaging the inner face of the disk 51 adjacent the inner face of thecylindrical wall of the sleeve 50. The outermost position of the sleeve50 is here effected by the engagement of the split ring 58 positioned inthe recess 59 formed in the sleeve 50 abutting against the shoulder 60formed on the inner sleeve 52.

The embodiments shown in Figs. 5 and 6 resemble the embodiment shown inFig. 3 rather than the embodiments shown in Figs. 1 and 4 since here toothe yieldable seat is not associated with an elongated sleeve, such asthe sleeve 20 of Fig. 1, or the sleeve 50 of Fig. 4.

In Fig. 5, as an instance, the disk 61 having the central opening 62 isslidably mounted in the cylindrical chamber formed in the upper part ofthe housing 63 having an opening 64 slightly less in diameter than thediameter of the disk 61 so that an annular lip 65 is provided to form astop for limiting the outward movement of the disk 61. Extendinginwardly from the disk 61 adjacent the opening 62 there is an annularshoulder 66 on the outside of which the outer coil of the weak spring 67engages, the inner coil of which is disposed inside of the shoulder 68formed on the contact disk 69. The inner coil of the strong spring 70engages the outer face of the shoulder 68 while the outer coil of thespring 70 engages the outer face of the annular shoulder 71 formed onthe disk 72 which is connected to the conductor 73.

In Fig. 6, a cylindrical chamber is formed at one side of the housing 74in which the disk 75 constituting the yieldable seat is slidablymounted, it having a pin receiving opening 76 and an annular shoulder 77to abut against the annular shoulder 78 of the housing 74 to determinethe outermost position of the disk 75. The weak spring 79 here has itsouter coil engaging the outer face of the inwardly extending annularshoulder 80 formed adjacent the opening 76, while its inner coil engagesthe inner face of the shoulder 81 formed on the contact disk 82. Inturn, the inner coil of the strong spring 83 engages the annular flange84 around the shoulder 81, and the outer coil of the spring 83 engagesthe outer face of the projection 85 which is electrically connected tothe conductor 86.

It will, of course, be apparent that the sleeves 20 and 50 aresubstantially parts of the disks 19 and 51, respectively, except thatthe outer ends of these disks are turned into aprons, constituting anexaggeration of the shoulders 41 and 77 of the embodiments shown inFigs. 3 and 6, which sleeves 20 and 50 and shoulders 41 and 77 may beomitted as shown in Fig. 5 when the outer edge of the disk 61 cooperateswith the shoulder 65 of the housing 63, or in turn, looking at theinvention from the standpoint of the sleeves 20 and 50, the shoulders 41and 77,

although shorter than the sleeves 20 and 50, are substantially sleevesand the outer periphery of the disk 61 of the embodiment shown in Fig. 5serves substantially the same function performed by the sleeves 26 and5t and shoulders 41 and 77, when cooperating with the inner face of thecylindrical wall of the housing 63 to position the disk during itsslidable motion and also to locate the outermost position of this disk.

It is obvious that various changes and modifications may be made to thedetails of construction without departing from the general spirit of theinvention as set forth in the appended claims.

I claim:

1. A socket having a yieldable seat for cooperating with a socket havinga fixed seat to support between the two a fluorescent lamp having asingle pin terminal at each end, characterized by a chambered housingcomposed of insulating material, having an opening and having aninternal abutment, a disk composed of insulating material having anarrow pin opening therein, said disk constituting a seat and beingslidable relative to said abutment, a single contact, a first spiralspring for normally spacing said contact from said disk a predetermineddistance when expanded and the coils of which spring in a radialdirection when contracted elfectively clearing said narrow pin openingand spacing said contact from said disk a shorter predetermineddistance, a second spiral spring in engagement with the said contactdisposed in said housing and tensed between said abutment and saidcontact, said housing and disk cooperating to enclose said springs andcontact, the second spring being less sensitive than said first springso that compression on the seat by the lamp will initially be mainlytaken up by said first spring until positive contact has beenestablished whereupon any further compression necessary to accommodatethe lamp between the socket fixtures will be absorbed by said secondspring.

2. The combination as set forth in claim 1, characterized by a metaldisk constituting said contact, and abutments formed on said housing tocooperate with said disk to determine its outermost position.

3. The combination as set forth in claim 1 in which said disk ischaracterized by a sleeve at its periphery slidably mounted in saidhousing and constituting the slidable support for said disk.

4. The combination as set forth in claim 1 in which said disk ischaracterized by a shoulder at its periphery slidably mounted in saidhousing and constituting the slidable support for said disk.

5. The combination as set forth in claim 1 in which an insulating Washeris interposed between said contact and said first yieldable means.

References Cited in the file of this patent UNITED STATES PATENTS2,412,826 Mills et a1. Dec. 17, 1946 2,446,154 Haven July 27, 19482,495,196 Kulka Jan. 17, 1950

